R

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Chapter 5: Using the Client Side Data Path

Client-Supplied FCS Passing

The transmission timing depicted in Figure 5-7shows the GEMAC core configured to have the FCS field passed in by the client. In this case, it is the responsibility of the client to ensure that the frame meets the Ethernet minimum frame length requirements as the GEMAC core will not perform any padding of the payload. See “Configuration Registers,” on page 78.

gtx_clk

tx_data[7:0]

tx_data_valid

tx_ack

tx_underrun

DA

SA

L/T

DATA

FCS

Figure 5-7:Frame Transmission with Client-supplied FCS

Client Underrun

Figure 5-8illustrates the timing of an aborted transfer. An example of this situation is a FIFO connected to the client interface that empties before a frame transfer is complete. When the client asserts tx_underrun during a frame transmission, the GEMAC core inserts an error code to corrupt the current frame, and then falls back to idle transmission. It is the responsibility of the client to re-queue the aborted frame for transmission.

When an underrun occurs, tx_data_valid may be asserted on the clock cycle after the tx_underrun assertion to request a new transmission.

gtx_clk

tx_data[7:0]

tx_data_valid

tx_ack

tx_underrun

DA SA L/T DATA

Figure 5-8:Frame Transmission with Underrun

48

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1-Gigabit Ethernet MAC v8.5 User Guide

 

 

UG144 April 24, 2009

Page 48
Image 48
Xilinx UG144 manual Client Underrun, 7Frame Transmission with Client-supplied FCS

UG144 specifications

The Xilinx UG144, a comprehensive user guide for the versatile Zynq-7000 SoC (System on Chip) architecture, serves as an essential resource for developers and engineers designing embedded systems. Emphasizing the blend of programmable logic and processing power, this guide highlights the array of features and technologies that make the Zynq-7000 series particularly attractive for a wide range of applications.

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